swift234

SILGen: Forward archetypes from alloc to init ctor

During type checking, fake up a "forwarding" substitution set for constructor decls that maps archetypes to themselves. This is goofy, but type-checking is the place that knows how to make ProtocolConformances, and I don't want to reinvent that. Use these forwarding substitutions in SILGen when emitting a generic allocating constructor so we can properly emit a call to the corresponding initializing constructor.

Swift SVN r4684